This invention relates to a granulation chamber for plastics materials, wherein the plastics material is extruded from an extruder head and granulated by means of a rotary star or spider arrangement of knives which is connected frontally to the extruder head.
Known are granulating chambers which comprise a hollow space of cylindrical shape, the top base whereof carries an extrusion head for the product to be granulated. Said head comprises an extrusion plate having orifices wherethrough the product, in a "spaghetti" form, is caused to emerge vertically continuously. A plurality of rotary knives arranged in a star or spider configuration are caused to shave the plate and cut into granules the product which is projected by centrifugal force against the walls of the granulating chamber. With certain products, the inner wall of the chamber is wet with a film of water which is effective to cool down the granules and prevent them from sticking to the wall.
In order to improve the output of such apparatus, one endeavors to increase the cutting rate as far as possible. However, above a certain speed range (above about 800 rpm's) the granules tend to rebound against the chamber walls and interfere with the successively formed granules, thus resulting in a mutual sticking condition.